In the related art, image forming apparatuses such as a multifunction peripheral (MFP) are used to form images on a sheet. In order to reuse a sheet, it is possible to form images with a decolorable colorant on a sheet. When a decolorable colorant is used in forming images, the sheet may be reused by erasing images later with an erasing apparatus.
The decolorable colorant is erased by applying high temperature heat thereto. Therefore, the erasing apparatus is used to heat the sheet and erase images formed on the sheet when reusing the sheet. The erasing apparatus heats the sheet by transporting the sheet through a press roller and a heat source. In this manner, the decolorable colorant is erased. Reusing sheets leads to saving sheets and may contribute to environmental protection. Erasing images formed on the sheet may be called “decolorization” in the description below.
Erasing apparatuses in the related art determine whether a sheet is reusable after erasing images printed with a decolorable colorant. Determination of whether a sheet is reusable depends on the presence or absence of a residue of an erased image and/or the state (deformation, damage, stains, and the like) of a sheet. For example, when images are formed, and post-processing such as punching and stapling is performed by a finisher, the sheet may be determined as nonreusable because of the damage. For this reason, post-processing such as punching and stapling is avoided.
In addition, in the erasing apparatus, there may be a limit on the number of times of reuse. For example, a sheet that is reused for N times (where N is the maximum allowable number of reuse) may be transported to a reject cassette as a nonreusable sheet.